This application claims the right of priority of Swiss patent application No. 2217/99 filed Dec. 3, 1999, the disclosure of which is incorporated herein by reference.
The invention relates to a method and a device for producing bags with three sealed edges and a welded-in closing profile. For example, European Patent Document No. B 667 288 discloses that a packaging foil is withdrawn gradually from a supply and is wound around a collar to form a cylindrical, downward moving tube. In the area adjacent to the two overlapping longitudinal edges of the foil, closing profile sections are supplied and inserted between the foil edges and are sealed to the foil with sealing jaws that are moved in time against the foils. The product to be packaged is filled in incrementally from the top and through the collar. The package formed in this way is then sealed with a transverse sealing seam by using sealing jaws that move in time, after which the package is separated. In the next step, the package is advanced and the following tube segment is filled. The closing profile sections are nearly as long as the inside distance between the transverse sealing seams. A similar device of this type, which also has a timed operation, is described in International Patent Application Publication No. WO 99/20529.
European Patent Document No. A 939 034 discloses another device for producing bags with three sealed edges. The device relates to a horizontal, tube-type bag-producing machine. The zipper is welded in as continuous ribbon between longitudinal edges of a continuously withdrawn foil that is folded around the products and the foil is simultaneously welded on along the free edges. Transverse sealing seams are formed in a transverse sealing station and the individual bags are then separated.
It is an object of the present invention to provide a method and a device of the aforementioned type that allows an increase in packaging speed. This object and others to become apparent as the application progresses, are accomplished by the invention. The method includes continuously withdrawing a packaging foil having two longitudinal edge regions with longitudinal edges from a first supply by means of a first feed unit. The packaging foil is folded. Cut-off lengths of closing profile sections are inserted between the two longitudinal edges of the packaging foil by means of a second feed unit so that successive closing profile sections are spaced apart. The two longitudinal edge regions are sealed substantially next to the longitudinal edges to form a longitudinal sealing seam on both sides onto the closing profile sections. A traverse seal is made using a transverse sealing device to effect transverse sealing of successive closing profile sections to thereby form individual bags and the individual bags are separated.
The device includes a first supply of a packaging foil having two longitudinal edge regions having longitudinal edges; a first feed unit for withdrawing the foil having a continuously driven first motor; a folding station for forming a flat tube from the foil so that the tube is open on one side and holds the products to be packaged; a second feed unit having a second motor for supplying and inserting cut-off lengths of closing profile sections between the two longitudinal edges of the foil; a first sealing station having two continuous first sealing jaws that are constantly positioned generally adjacent to each other for sealing the closing profile sections to respective longitudinal edge regions to substantially meet to the longitudinal edges of the foil; a second sealing station having at least substantially adjacent second sealing jaws for the sealing the two foil edges in longitudinal direction in a location substantially next to the longitudinal edges of the foil and outside of ends of the cut-off lengths of closing profile sections; a third sealing station for forming transverse seams between the ends of successive cut-off lengths of closing profile sections; and a separating device that cuts the tube transversely at least approximately in the center of the transverse seams. At least a portion of the first feed unit is arranged downstream of the first and second sealing stations.